Multiple mode transmitters, receivers and transceivers are, for purposes of this document, devices that utilize radio frequency circuitry for communication using multiple transceivers, transmitters and/or receivers. One example might be a radio frequency (RF) wireless cellular telephone device using 800 MHz CDMA (Code Division Multiple Access) technology as a primary communication technology. In addition, the device may incorporate a 1575 MHz GPS (Global Positioning System) receiver that permits the user and the device to determine positioning coordinates from the GPS satellite system. The device may also incorporate, for example, a Bluetooth® compliant 2400 MHz transceiver for carrying out communications with other Bluetooth® standard compliant devices. Such a device therefore can utilize three receivers and two transmitters for carrying out the specified communications.
According to conventional lines of thinking, the above scenario would be implemented using three separate receivers and two transmitters (the GPS device having no associated transmitter) connected to multiple antennas in order to achieve the RF communications. Thus each transmitter, receiver and/or transceiver uses its own resources (i.e., transmitter circuits, receiver circuits and antennas) as dedicated resources. When a particular mode of operation is inactive, there is no facility to marshal the available resources of that inactive mode to improve the performance of the resources currently in use.
Several communications methods have been previously devised to advantageously utilize multiple antennas. Recently, a technology known as MIMO (Multiple Input Multiple Output) has been proposed that utilizes multiple antennas at the input of a receiver and/or multiple antennas at the output of a transmitter to increase the capacity of a communications link by providing multiple independent transmission paths. Spatial, polarization, or pattern diversity provided by multiple antennas can also be advantageously utilized to provide improved resistance to fading by use of the antenna or combination of antennas that provides the best signal. Still, such systems cannot take advantage of idle resources in multiple mode receivers to enhance system performance.